1. Field of the Invention
The present invention relates to a method of separating carbon dioxide from a gas mixture, and, more particularly, to a method of separating carbon dioxide from a gas mixture using hemocyte or extrapallial fluid, which is known to be a biopolymer synthesizing calcium carbonate in sea water.
2. Description of the Related Art
A bivalve shell is mainly composed of calcium carbonate (95 wt %), and bivalves synthesize calcium carbonate using carbon dioxide and calcium ions present in sea water. Among organic polymers participating in such a shell synthesis process, carbonic anhydrase is well known. Carbonic anhydrase mainly functions to convert carbon dioxide present in sea water into bicarbonate ions (HCO3−), and these bicarbonate ions are used to synthesize calcium carbonate.
The process of hydrating carbon dioxide using carbonic anhydrase is as follows.E.ZnH2OEZnOH−+H+E.ZnOH−+CO2EZnHCO3−E.ZnHCO3−EZnH2O+HCO3−
In the process, zinc (Zn), which is located in the carbonic anhydrase, reacts with a water molecule, thus forming a hydroxy ion, which then reacts with carbon dioxide, thus producing a bicarbonate ion.
As a well-known method of treating carbon dioxide from a gas mixture, there is a wet process of treating carbon dioxide from a gas mixture using an aqueous amine solution as an absorbing solution (refer to Korean Patent Application No. 10-2006-0017946).
However, the wet process is problematic in that, when the aqueous amine solution is used, apparatuses are easily corroded, an absorbent is deteriorated, and a large amount of regeneration heat is required, thus increasing process costs.
As conventional technologies of treating carbon dioxide using a biopolymer as an absorbent, U.S. Pat. No. 6,524,843 discloses a method of separating and removing carbon dioxide from a gas mixture by converting carbon dioxide into bicarbonate ions using a countercurrent bioreactor charged with carbonic anhydrase, in which a gas mixture including carbon dioxide is introduced into the bottom of the bioreactor and a liquid solvent (water) is introduced into the top of the bioreactor, and U.S. Pat. No. 7,132,090, which was granted to General Motors Corporation, discloses a process for converting carbon dioxide into calcium carbonate, in which carbon dioxide, discharged from factories or power plants, is primarily mixed in water and then passes through a porous membrane containing carbonic anhydrase, so that the carbon dioxide is converted into bicarbonate ions, and the bicarbonate ions are converted into calcium carbonate. However, Korean Patents relating to the above technologies have not been filed yet.
Meanwhile, carbonic anhydrase includes zinc (Zn) ions, which act as active sites for adsorbing carbon dioxide.
However, the carbonic anhydrase cannot be easily reproduced due to the presence of the zinc (Zn), and is an expensive enzyme protein, having a market price of several hundreds of thousands of Won for several milligrams, which impedes the use of carbonic anhydrase in large quantities.